1. Field of the Invention
The present invention relates generally to surgical apparatus and, more particularly, to a hand held drill jig intended for use during surgery to locate and maintain a central axis through a femoral head and an associated femoral neck enabling a blind bore to be drilled into the femoral head oriented to the central axis.
2. Description of the Prior Art
There are instances which hip surgery does not require complete replacement of a femoral head. Instead, it is a relatively common procedure to somewhat reshape the femoral head, then attach a shell prosthesis covering the reshaped natural head. In some instances the shell prosthesis has a downwardly projecting pin so as to locate and hold the shell in proper position. Such a situation is disclosed in U.S. Pat. No. 4,246,895. In some other instances, as disclosed in U.S. Pat. No. 4,224,699, there is no downwardly projecting pin integral with the shell, but rather an appropriate screw which is used to fixedly mount the shell into position.
In either instance, it is necessary, or at least desirable, to provide a bore to receive the downwardly extending pin or screw. For this purpose, it has been common practice for the surgeon to drill into the femoral head from a superior position while firmly gripping the femur in one hand and operating an electric drill motor with the other hand without guides of any nature to aid him in the process. Thus, the axis of the resulting bore would be randomly disposed, as determined visually by the surgeon and further as determined by the steadiness with which he could manually maintain the relative positioning between the bone on one hand and the drill motor and its associated drill bit in the other hand.